1. Field of the Invention
The present invention relates to an image processing apparatus, and more particularly to control of an image processing unit (board) which is connected to a general-purpose bus such as a PCI (Peripheral Component Interconnect) bus or the like.
2. Related Background Art
Conventionally, a digital copying machine which has functions to read an original being a copy target, store image data representing the read original in a storage such as a hard disk or the like, and then output the stored image data to other printer through a network is known. That is, since the digital copying machine of such a type has the plural functions which includes a print function to input print data from an external computer and print the input print data, a facsimile reception function to receive facsimile data from a public network, and the like, it is called a multifunctional apparatus.
Furthermore, since the multifunctional apparatus is equipped with a general-purpose bus such as a PCI bus or the like, plural image processing boards such as an image magnification change processing board and the like can be connected to the multifunctional apparatus according to a user's demand.
However, when such a system to add the image processing board to the multifunctional apparatus through the PCI bus is adopted, the multifunctional apparatus becomes expandable. However, since the general-purpose bus is time-divisionally used, it is necessary to provide many image memories (page memories) on each image processing board so that the process is not interrupted on the way. As a result, this increases the cost of an entire system.
Incidentally, if data from the PCI bus and its timing are subjected to raster conversion, the converted data can be processed only by a line memory such as an FIFO (first-in, first-out) memory or the like. However, even in such a case, if the PCI bus is occupied by other image processing board, the data can not be input from the bus, and also processed image data can not be output to the bus. Therefore, a problem that the data is lost because the line memory such as the FIFO memory overflows occurs, whereby such a system does not necessarily have stability.